This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the presently described embodiments. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present embodiments. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
This disclosure generally relates to a real-time, in-situ, and non-invasive laboratory apparatus and method for evaluating the performance and design of materials for use in a wellbore, such as cement and drilling fluids.
Oil and gas wells extend from the surface to one or more subterranean formations of rock containing oil and/or gas. The well is typically cased by cementing a steel or other suitable casing in the wellbore. The casing stabilizes the sides of the wellbore, prevents pollution of fresh water reservoirs, and/or prevents fluids from zones other than oil and gas producing zones from entering the wellbore.
When cementing casing, wet cement slurry is pumped down the wellbore to fill the annular space defined between the casing and the rock walls. The cement protects the casing and prevents water and other fluids from entering the space between the casing and rock walls of the wellbore. Cement volume change due to hydration is an important consideration for engineers designing and supervising the cement slurry. Failure to account for changes in cement volume (i.e., shrinkage or expansion) may lead to debonding and in some cases failure of the cement sheath, leading to a loss of zonal isolation. Laboratory technicians test and select the cement slurry and additives to optimize cement performance at particular downhole conditions.
When drilling a well, a drilling fluid (e.g., drilling mud) is pumped down the drill string to facilitate the drilling process, including suspending cuttings generated during drilling, controlling pressure in the wellbore, stabilizing exposed formation, providing buoyancy, and cooling and lubricating the drill bit. Over time as the drilling fluid is pumped downhole, a cake of solids forms on the wall of the formation as liquid from the drilling fluid filters into the formation. This cake is commonly referred to as a “mud cake.” The erodibility of the mud cake is an important consideration for engineers designing and supervising the drilling operations.
Cement compositions and drilling fluids are designed for a variety of wellbore conditions, which may vary in depth, temperature, and pressure. In designing a cement composition or drilling fluid for a wellbore, a number of potential slurries and/or fluids are typically tested in a laboratory for pumpability, safe placement time, compressive strength, filtration rate, erodibility, etc. Ideally, cement compositions and drilling fluids should be analyzed at actual wellbore conditions, such as the wellbore pressure and temperature, and their performance monitored in real time. Existing measurement techniques and apparatuses for measuring cement shrinkage/expansion and erodibility and performing goniometry are not able to achieve measurements in real time at high pressure and high temperature conditions, in situ, or non-invasively.
There continues to be a need for such measurement techniques in order to design cement compositions and drilling fluids suitable for use in a wellbore at particular conditions.
The illustrated figures are only exemplary and are not intended to assert or imply any limitation with regard to the environment, architecture, design, or process in which different embodiments may be implemented.